:root {
    --bg-color: #0f172a;       /* Dark Slate */
    --card-bg: #1e293b;        /* Lighter Slate */
    --text-primary: #f8fafc;   /* White-ish */
    --text-secondary: #94a3b8; /* Grey text */
    --accent: #38bdf8;         /* Cyan/Blue Accent */
    --accent-hover: #0ea5e9;
    --font-main: 'Inter', sans-serif;
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    background-color: var(--bg-color);
    color: var(--text-primary);
    font-family: var(--font-main);
    line-height: 1.6;
}

a {
    text-decoration: none;
    color: inherit;
    transition: 0.3s;
}

ul {
    list-style: none;
}

/* Container Utility */
.container {
    max-width: 1000px;
    margin: 0 auto;
    padding: 4rem 1.5rem;
}

h2 {
    font-size: 2rem;
    margin-bottom: 2rem;
    color: var(--accent);
    text-transform: uppercase;
    letter-spacing: 1px;
}

/* Navigation */
nav {
    position: fixed;
    top: 0;
    width: 100%;
    background: rgba(15, 23, 42, 0.9);
    backdrop-filter: blur(10px);
    z-index: 1000;
    border-bottom: 1px solid rgba(255,255,255,0.05);
}

.nav-container {
    max-width: 1200px;
    margin: 0 auto;
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1rem 1.5rem;
}

.logo {
    font-weight: 700;
    font-size: 1.5rem;
    color: var(--accent);
}

.nav-links {
    display: flex;
    gap: 2rem;
}

.nav-links a {
    color: var(--text-secondary);
    font-size: 0.9rem;
    font-weight: 500;
}

.nav-links a:hover {
    color: var(--accent);
}

.btn-small {
    border: 1px solid var(--accent);
    padding: 0.5rem 1rem;
    border-radius: 4px;
    color: var(--accent) !important;
}

.btn-small:hover {
    background: var(--accent);
    color: var(--bg-color) !important;
}

/* Hero Section (Split Layout) */
#about {
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 6rem 1.5rem 2rem; /* Top padding for navbar */
}

.hero-wrapper {
    display: flex;
    align-items: center;
    justify-content: space-between; /* Pushes text and image apart */
    gap: 4rem;
    max-width: 1100px;
    margin: 0 auto;
    width: 100%;
}

.hero-content {
    flex: 1; /* Takes up available space */
    max-width: 600px;
}

.tagline {
    color: var(--accent);
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 2px;
    font-size: 0.9rem;
    margin-bottom: 1rem;
    display: block;
}

h1 {
    font-size: 3.5rem;
    font-weight: 800;
    line-height: 1.1;
    margin-bottom: 1.5rem;
    background: linear-gradient(to right, #f8fafc, #94a3b8);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
}

.hero-text {
    font-size: 1.2rem;
    color: var(--text-secondary);
    margin-bottom: 2rem;
    line-height: 1.7;
}

.hero-buttons {
    display: flex;
    gap: 1rem;
}

.btn-primary {
    background: var(--accent);
    color: var(--bg-color);
    padding: 0.8rem 2rem;
    border-radius: 4px;
    font-weight: 600;
}

.btn-primary:hover {
    background: var(--accent-hover);
}

.btn-secondary {
    border: 1px solid var(--text-secondary);
    color: var(--text-primary);
    padding: 0.8rem 2rem;
    border-radius: 4px;
    font-weight: 600;
}

.btn-secondary:hover {
    border-color: var(--accent);
    color: var(--accent);
}

/* Hero Image Styling */
.hero-image {
    flex-shrink: 0;
}

.hero-image img {
    width: 320px;
    height: 320px;
    object-fit: cover;
    border-radius: 50%;
    border: 4px solid var(--accent);
    box-shadow: 0 0 30px rgba(56, 189, 248, 0.2);
    transition: transform 0.3s ease;
}

.hero-image img:hover {
    transform: scale(1.05);
}

/* Skills Grid */
.skills-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 2rem;
}

.skill-card {
    background: var(--card-bg);
    padding: 2rem;
    border-radius: 8px;
    border: 1px solid rgba(255,255,255,0.05);
    transition: transform 0.3s;
}

.skill-card:hover {
    transform: translateY(-5px);
    border-color: var(--accent);
}

.skill-card i {
    font-size: 2rem;
    color: var(--accent);
    margin-bottom: 1rem;
}

.skill-card h3 {
    margin-bottom: 0.5rem;
    font-size: 1.2rem;
}

.skill-card p {
    color: var(--text-secondary);
    font-size: 0.9rem;
}

/* Experience Timeline */
.timeline {
    border-left: 2px solid var(--card-bg);
    margin-left: 1rem;
    padding-left: 2rem;
}

.timeline-item {
    margin-bottom: 3rem;
    position: relative;
}

.timeline-item::before {
    content: '';
    position: absolute;
    left: -2.6rem;
    top: 0.5rem;
    width: 1rem;
    height: 1rem;
    background: var(--accent);
    border-radius: 50%;
    border: 4px solid var(--bg-color);
}

.timeline-date {
    color: var(--accent);
    font-size: 0.9rem;
    font-weight: 600;
    margin-bottom: 0.5rem;
}

.timeline-content h3 {
    font-size: 1.4rem;
}

.timeline-content h4 {
    color: var(--text-secondary);
    font-weight: 400;
    margin-bottom: 1rem;
}

.timeline-content ul {
    list-style: disc;
    margin-left: 1.5rem;
    color: #cbd5e1;
}

.timeline-content li {
    margin-bottom: 0.5rem;
}

/* Project Grid */
.project-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 2rem;
}

.project-card {
    background: var(--card-bg);
    padding: 2rem;
    border-radius: 8px;
    border: 1px solid rgba(255,255,255,0.05);
    display: flex;
    flex-direction: column;
    justify-content: flex-start;
    transition: 0.3s;
}

.project-card:hover {
    border-color: var(--accent);
}

.project-role {
    display: inline-block;
    align-self: flex-start;
    background: rgba(56, 189, 248, 0.1);
    color: var(--accent);
    padding: 0.2rem 0.8rem;
    border-radius: 50px;
    font-size: 0.8rem;
    margin-bottom: 1rem;
    margin-top: 0.5rem;
}

.project-card p {
    color: var(--text-secondary);
    font-size: 0.95rem;
}

/* Education & Publications */
.education-grid {
    display: grid;
    gap: 1.5rem;
}

.edu-card {
    border-bottom: 1px solid var(--card-bg);
    padding-bottom: 1.5rem;
}

.pub-list li {
    margin-bottom: 1.5rem;
    color: var(--text-secondary);
    border-left: 3px solid var(--accent);
    padding-left: 1rem;
}

.pub-list strong {
    color: var(--text-primary);
    display: block;
    margin-bottom: 0.3rem;
}

/* Footer */
footer {
    text-align: center;
    background: var(--card-bg);
    padding: 4rem 1.5rem;
    margin-top: 4rem;
}

.social-links {
    display: flex;
    justify-content: center;
    gap: 1.5rem;
    margin: 2rem 0;
    flex-wrap: wrap;
}

.social-links a {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    color: var(--text-primary);
    border: 1px solid var(--text-secondary);
    padding: 0.5rem 1.5rem;
    border-radius: 50px;
}

.social-links a:hover {
    border-color: var(--accent);
    color: var(--accent);
}

.copyright {
    color: var(--text-secondary);
    font-size: 0.8rem;
}

/* Mobile Responsive */
@media (max-width: 900px) {
    /* Stack Hero Section Vertically */
    .hero-wrapper {
        flex-direction: column-reverse; /* Puts image on top if desired, or 'column' for image bottom */
        text-align: center;
        gap: 2rem;
    }

    .hero-content {
        max-width: 100%;
    }

    .hero-buttons {
        justify-content: center;
    }

    .hero-image img {
        width: 200px;
        height: 200px;
    }

    h1 {
        font-size: 2.5rem;
    }

    .nav-links {
        display: none; /* Hides nav links on small screens */
    }
    
    .timeline {
        border-left: none;
        margin-left: 0;
        padding-left: 0;
    }
    
    .timeline-item::before {
        display: none;
    }
}